TW201619219A - Modified polypropylene resin, polypropylene resin foamed sheet, foamed resin container, and method for producing modified polypropylene resin - Google Patents

Abstract

Provided is a modified polypropylene resin that is able to obtain a foam sheet having a low open-cell ratio by using a modified polypropylene resin exhibiting a specific viscoelasticity.

Description

Modified polypropylene resin, polypropylene resin foamed sheet, foamed resin container, and modified polypropylene resin Cross-references to related applications

The present application claims the priority of Japanese Patent Application No. Hei. No. Hei. No. Hei. No. Hei. No. Hei.

The present invention relates to a modified polypropylene-based resin modified with a polypropylene-based resin, a polypropylene-based resin foamed sheet, and a method for producing a modified polypropylene-based resin produced by modifying a polypropylene-based resin.

In the past, polypropylene resins are excellent in mechanical properties and chemical resistance, and thus are used as raw materials for various molded articles.

A molded article made of a polypropylene resin is generally produced by extrusion molding, blow molding, foam molding, or the like.

However, since the polypropylene resin generally has crystallinity, the viscosity and the melt tension at the time of melting are low.

Therefore, in particular, when a foamed molded article made of a polypropylene resin or the like is desired, it is difficult to obtain a foamed sheet having a low open cell ratio.

In order to solve such a problem, it has been reviewed that the polypropylene resin is further modified with an aromatic vinyl monomer such as a styrene monomer to adjust the melting characteristics.

However, when the amount of deformation per unit time is increased by the polymer in a molten state and the tensile viscosity is measured, in a general polymer, the value of the amount of deformation and the value of the tensile viscosity are substantially linear.

On the other hand, a specific polymer exhibits a property that the tensile viscosity rises sharply with a deformation amount as a boundary.

Therefore, such a property is called "deformation hardenability" and the like.

Patent Document 1 listed below discloses a method of obtaining a modified polypropylene resin having "deformation hardenability".

In the case of the reaction of the styrene monomer in an amount of 10 parts by mass or more based on 100 parts by mass of the polypropylene resin, the reaction of the styrene monomer is carried out in an amount of only 2 parts by mass. The deformation hardenability which cannot be exhibited at the time makes the rod-shaped foam have a good foaming state.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 09-188728

A polypropylene-based resin which imparts excellent deformation-hardenability by reforming should be advantageous for rapid growth of bubbles in foam molding or the like. In the case of preventing the bubble film from being ruptured by the rapid elongation of the film, a foamed molded article having a low continuous cell ratio is formed.

However, conventionally, even if a modified polypropylene resin excellent in deformation hardenability is used, it is difficult to obtain a foamed molded article having a low open cell ratio.

This is because the modified resin exhibits deformation hardenability but does not form a specific viscoelasticity.

Such a problem is more remarkable in the case of extrusion foaming by a circular die or the like to produce a foamed sheet than in the case of a rod-shaped foamed molded body and a plate-like foamed molded body which are extruded by using a trimming die.

Further, in the production of the foamed sheet, in particular, in the production of the foamed sheet, even if the modified polypropylene resin having good deformation hardenability at the time of formation is difficult to obtain a foamed sheet having a low continuous cell ratio, it is extremely necessary. Countermeasures, however, such countermeasures have not yet been established.

An object of the present invention is to provide a modified polypropylene-based resin which can easily obtain a foamed sheet having a low open cell ratio, in order to satisfy such a need for such cut.

The inventors of the present invention have deliberately conducted a review to solve the above problems, and found that a modified polypropylene-based resin which exhibits a specific viscoelasticity at the time of giving relatively gentle deformation has a foamed sheet having a low open cell ratio.

In other words, in order to solve the above problems, the modified polypropylene resin of the present invention is obtained by reacting an aromatic vinyl monomer in a polypropylene resin, and is obtained by measuring a dynamic viscoelasticity at a frequency of 200 ° C. The phase angle is 30° or more and 70° or less at a frequency of 0.01 Hz.

Further, the polypropylene-based resin foamed sheet of the present invention comprises a modified polypropylene-based resin obtained by reacting an aromatic vinyl monomer in a polypropylene-based resin, and the modified polypropylene-based resin is at a frequency of 200 ° C The phase angle obtained by the dispersion dynamic viscoelasticity measurement is 30° or more and 70° or less at a frequency of 0.01 Hz.

Moreover, the foamed resin container of the present invention is obtained by thermoforming such a foamed sheet of the polypropylene resin.

Moreover, the method for producing a modified polypropylene resin of the present invention is a method for producing a modified polypropylene resin by reacting an aromatic vinyl monomer in a polypropylene resin, and the production method is a polypropylene-containing resin. The resin composition of the resin, the organic peroxide, and the aromatic vinyl monomer is melt-kneaded, and the phase angle obtained by measuring the dynamic viscoelasticity at a frequency of 200 ° C at a frequency of 0.01 Hz is 30° or more and 70° or less. In the above-mentioned resin composition of the above-mentioned melt-kneading, the above-mentioned resin composition is melted and kneaded, and the organic peroxide is contained in an amount of 0.1 part by mass or more and 1.5 parts by mass or less based on 100 parts by mass of the polypropylene resin. 100 parts by mass of the polypropylene resin contains the above aromatic vinyl monomer in a proportion of 0.1 part by mass or more and 10 parts by mass or less.

According to the present invention, a modified polypropylene-based resin suitable for foaming can be obtained, and a foamed sheet having a low continuous cell ratio can be easily obtained.

Hereinafter, embodiments of the present invention will be described.

(modified polypropylene resin)

The modified polypropylene resin in the present embodiment has a phase angle obtained by measuring the dynamic viscoelasticity at a frequency of 200 ° C at a frequency of 0.01 Hz of 30° or more and 70° or less.

In the frequency dispersion dynamic viscoelasticity measurement, the influence of the viscosity term is easily exhibited in the low frequency range.

That is, the modified polypropylene resin of the present embodiment has a small phase angle in a low frequency range, and thus does not easily cause "shear" between molecules.

Therefore, the modified polypropylene-based resin of the present embodiment exhibits a relatively good stretch when foamed and formed into a foamed sheet. Therefore, it is possible to suppress the bubble film from being thinned and become thinner with the growth of the bubble, which is advantageous in obtaining a hair having a low continuous cell ratio. Bubble sheet.

Further, the phase angle described above can be obtained as follows.

(Method of calculating phase angle)

The dynamic viscoelasticity measurement was measured in a temperature control system CTD450 using a viscoelasticity measuring device PHYSICA MCR301 (manufactured by Anton Paar Co., Ltd.).

First, a modified polypropylene resin obtained from a sample was subjected to heating in a hot press at a temperature of 200 ° C for 5 minutes to obtain a disk sample having a diameter of 25 mm and a thickness of 3 mm.

Next, the sample was placed on a plate of a viscoelasticity measuring apparatus heated to a measurement temperature (200 ° C) and melted by heating for 5 minutes under a nitrogen atmosphere.

Then, use a parallel plate with a diameter of 25 mm, so that the parallel plate The sample was pressed while the interval was 2.0 mm, and the modified polypropylene resin extruded by the sheet was removed.

After the measurement temperature is ±1 ° C, the sample is heated for another 5 minutes, and is carried out under the conditions of 5% deformation, frequency 0.01 to 100 (Hz), number of measurement points 21 (5 points/row), and measurement temperature of 200 ° C. Dynamic viscoelasticity measurement, determination of phase angle δ (°).

Again, the assay begins with a high frequency end (100 Hz).

Then, the phase angle δ at a frequency of 0.01 Hz was obtained.

Such a modified polypropylene-based resin can be obtained by reacting a resin composition containing (A) a polypropylene-based resin, (B) an organic peroxide, and (C) an aromatic vinyl monomer.

In particular, the modified polypropylene resin of the present embodiment can be easily obtained by melt-kneading a resin composition containing 0.1 parts by mass based on 100 parts by mass of the polypropylene resin. The above-mentioned organic vinyl peroxide is contained in an amount of 0.1 part by mass or more and 10 parts by mass or less based on 100 parts by mass of the polypropylene-based resin.

The modified polypropylene resin of the present embodiment is suitable for forming a foamed molded article having a good appearance and good strength.

In the modified polypropylene resin of the present embodiment, bubble cracking is less likely to occur inside during foaming, so that a foamed molded article having a low open cell ratio and a good appearance can be obtained.

Meanwhile, the modified polypropylene-based resin of the present embodiment has an advantage that it is easy to produce a foamed sheet having a low open cell ratio.

The resin composition used in the modified polypropylene resin of the present embodiment is preferably a "(D) radical scavenger" and may contain "(A) to (D)" (( E) Other ingredients".

Hereinafter, each component used in the preparation of the modified polypropylene resin of the present embodiment will be described.

[(A) Polypropylene resin]

(A) A polypropylene-based resin obtained by polymerizing a propylene monomer.

In the present embodiment, one or more kinds of the homopolymer of the propylene monomer and the copolymer of the main component of the propylene monomer as the constituent unit are contained in the resin composition as the (A) polypropylene resin.

For the copolymer, for example, the ratio of propylene to the constituent unit is preferably 50% by mass or more, the proportion of propylene is preferably 80% by mass or more, and the proportion of propylene is particularly preferably 90% by mass or more.

The copolymerization may be random copolymerization or block copolymerization.

When the polypropylene resin is a copolymer, the component other than the propylene monomer is preferably one or more selected from the group consisting of an ethylene monomer and an α-olefin monomer having 4 to 8 carbon atoms, and an ethylene monomer and a 1-butene monomer. One or more of them are more preferable.

Specific examples of the (A) polypropylene-based resin include a propylene homopolymer, a propylene random polymer, and a propylene block polymer.

(A) The polypropylene-based resin is preferably a homopolymer of a propylene monomer, and more preferably a propylene homopolymer.

(A) The polypropylene resin is preferably a melt mass flow rate (MFR) of 0.2 g/10 min or more.

(A) a polypropylene-based resin, usually at a lower value of the melt mass flow rate, It is advantageous in imparting high melt tension to the modified polypropylene resin.

On the other hand, (A) the polypropylene-based resin generally has a higher burden on the machine when the resin composition is melt-kneaded by an extruder or the like at a higher value of the melt mass flow rate.

In this case, the melt mass flow rate (MFR) of the (A) polypropylene resin is preferably 0.3 g/10 min or more, more preferably 0.5 g/10 min or more.

Further, the melt mass flow rate (MFR) is preferably 15 g/10 minutes or less, more preferably 10 g/10 minutes or less, and still more preferably 5 g/10 minutes or less.

Further, the MFR of the (A) polypropylene-based resin is measured under the conditions of a test temperature of 230 ° C and a load of 21.18 N in accordance with the method of JIS of JIS K7210:1999.

[(B) Organic peroxide]

The organic peroxide (B) of the present embodiment is not particularly limited as long as it has hydrogen abstracting ability to the polypropylene resin, and examples thereof include hydroperoxides and dialkyl peroxides. Ester peroxide, dimercapto peroxide, dicarbonate peroxide, ketal peroxide and ketone peroxide.

Examples of the above hydroperoxide include p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide, and tert-butyl hydroperoxide.

Examples of the above dialkyl peroxides include diisopropyl phenyl peroxide, di-tert-butyl peroxide, and 2,5-dimethyl-2,5-di (third butyl) Base oxidized) - hexyne-3 and the like.

Examples of the ester peroxides include, for example, t-butylperoxy-2-ethylhexyl carbonate, third hexylperoxyisopropyl monocarbonate, and third hexylperoxybenzoate, Tributyl peroxybenzoate, t-butyl peroxylaurate, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxyacetate, 2,5-Dimethyl-2,5-di(benzimidyl peroxy)hexane and tert-butylperoxyisopropyl monocarbonate.

Examples of the above-mentioned dimercapto peroxides include, for example, benzhydryl peroxide, bis(4-methylbenzhydryl) peroxide, and bis(3-methylbenzhydryl). Oxide, etc.

Examples of the above-mentioned dicarbonate peroxide include di(2-ethylhexyl)peroxydicarbonate and diisopropylperoxydicarbonate.

Examples of the above ketal peroxide include, for example, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane and 1,1-di-t-butyl group. Oxidized cyclohexane, 2,2-di(t-butylperoxy)butane, n-butyl-4,4-di(t-butylperoxy)valerate and 2,2-di(4, 4-di-t-butylperoxycyclohexyl)propane and the like.

Examples of the ketone peroxide include methyl ethyl ketone peroxide and acetyl ketone peroxide.

The (B) organic peroxide of the present embodiment is preferably an ester peroxide, a dimercapto peroxide or a dicarbonate peroxide.

The above organic peroxide is preferably a structure having a structure represented by the following formula (X).

(wherein R ¹ represents a substituted or unsubstituted phenyl group or a substituted or unsubstituted alkoxy group, and R ² represents a monovalent organic group.)

Further, the formula (X-), when the "R ^1" is alkoxy, "R ^1" to 3-8 branched structure of the alkyl group having a carbon number (e.g.: isopropyl, t-butyl, The alkoxy group having an oxygen atom bonded to the third hexyl group, 2-ethylhexyl group or the like is preferred.

When "R ¹ " is other than the alkoxy group of the oxygen atom bonded to the 2-ethylhexyl group, the oxygen atom is preferably bonded to the secondary or tertiary carbon, and "R ¹ " has the following The configuration shown by the formula (Y) is better.

(In the formula, "R ¹¹ " and "R ¹² ", either one is a methyl group and the other is a hydrogen atom; "R ¹⁴ " represents a linear alkyl group having 1 to 6 carbon atoms, and "R ¹³ " represents two Grade carbon or tertiary carbon.)

Further, when "R ¹ " is an optionally substituted or unsubstituted phenyl group, "R ¹ " is preferably an unsubstituted phenyl group or a substituted phenyl group in which one hydrogen atom is substituted with a methyl group.

Further, "R ² " is preferably a high-volume structure having a branched alkyl group or a phenyl group.

Specifically, it is preferred to have a structure represented by the following formula (Z).

(wherein "R ²¹ " in the formula" represents a straight-chain alkyl group having 1 to 6 carbon atoms or a monovalent organic group having a phenyl group.

Examples of the organic peroxide having a structure represented by the general formula (X) include, for example, t-butylperoxy-2-ethylhexyl carbonate, and third hexylperoxyisopropyl monocarbonate. Tributyl peroxyisopropyl monocarbonate, third hexyl peroxybenzoate, 2,5-dimethyl-2,5-bis(benzhydrylperoxy)hexane, diphenylformamidine A base peroxide, bis(4-methylbenzylidene) peroxide, diisopropylperoxydicarbonate, and the like.

The content of the (B) organic peroxide in the resin composition is 0.1 parts by mass or more and 1.5 parts by mass or less based on 100 parts by mass of the (A) polypropylene resin.

In the modified polypropylene resin of the present embodiment, when the content of the (B) organic peroxide is too small, the reactivity of the resin composition is lowered, so that it is not possible to exhibit a good reforming effect.

When the content of the (B) organic peroxide is too large, the modified polypropylene resin of the present embodiment tends to cause a decomposition reaction of the polypropylene resin during melt kneading.

When the decomposition reaction of the polypropylene resin is excessively caused during melt kneading, there is a concern that it is difficult to exhibit a good reforming effect.

That is, by making the (B) organic peroxide content of the above resin composition When the amount is 0.1 parts by mass or more and 1.5 parts by mass or less, a modified polypropylene resin having excellent melt tension can be produced. Therefore, the necessity of highly precisely controlling the reaction conditions during melt kneading can be reduced.

In the present embodiment, in order to more reliably produce a modified polypropylene resin having excellent melt tension, the content of the (B) organic peroxide is 0.3 parts by mass based on 100 parts by mass of the (A) polypropylene resin. The above is better.

In addition, the content of the (B) organic peroxide is preferably 1.0 part by mass or less based on 100 parts by mass of the (A) polypropylene resin.

[(C) Aromatic Ethylene Monomer]

(C) An aromatic vinyl monomer which is a component which is chemically bonded to (A) a polypropylene-based resin to form a branched structure and simultaneously crosslinks the polypropylene-based resin to function as a crosslinking agent.

The (C) aromatic vinyl monomer contained in the resin composition of the present embodiment may be one type or two or more types.

Examples of the above aromatic vinyl monomer include styrene; o-methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, β-methyl styrene, and dimethyl Methylstyrene such as styrene and trimethylstyrene; α-chlorostyrene, β-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, dichlorostyrene, trichlorobenzene Vinyl styrene such as ethylene; brominated styrene such as o-bromostyrene, m-bromostyrene, p-bromostyrene, dibromostyrene or tribromostyrene; o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, Fluorinated styrene such as difluorostyrene or trifluorostyrene; o-nitrene, m-nitrostyrene, p-nitrostyrene, dinitrostyrene, trinitrostyrene Equal nitrostyrene; vinyl phenol such as o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, dihydroxystyrene, trishydroxystyrene; o-divinylbenzene, m-divinylbenzene, p-divinyl Divinylbenzene such as benzene; isopropenylbenzene such as o-diisopropenylbenzene, m-diisopropenylbenzene or p-diisopropenylbenzene.

Among them, aromatic vinyl monomer is preferably styrene.

The content of the (C) aromatic vinyl monomer in the resin composition may be 0.1 parts by mass or more and 10 parts by mass or less based on 100 parts by mass of the (A) polypropylene-based resin.

When the content of the (C) aromatic vinyl monomer is too small, the modified polypropylene resin may not completely form a branched or crosslinked structure during melt kneading, and the resin may not be completely inhibited from decomposition by the peroxide. There will be concerns about not being able to perform well.

When the content of the (C) aromatic vinyl monomer is too large, the modified (C) aromatic vinyl monomer is likely to be unreacted in the melt-kneading, and thus the modified polypropylene resin is contained. Excessive oligomers, or the problem of turbidity due to microphase separation, etc.

In the resin composition, the content of the (C) aromatic vinyl monomer is from 0.1 part by mass to 10 parts by mass, and a modified polypropylene system capable of obtaining a foamed sheet having a low continuous cell ratio is produced. The resin thus reduces the need for highly precise control of the reaction conditions during melt kneading.

[(D) Radical Scavenger]

In order to obtain the above-mentioned modified polypropylene resin, the above resin composition preferably contains a (D) radical scavenger which can control its reactivity.

Using (D) radical scavenger, can effectively improve the modified polypropylene tree The melt tension of the fat.

That is, the (D) radical scavenger is effective in using a modified polypropylene resin to obtain a resin foam having a good appearance.

(D) a radical scavenger which is reactive with an alkyl radical species.

(D) The radical scavenger is preferably bonded to an aromatic vinyl monomer which is bonded to an alkyl radical.

(D) The radical scavenger may be used alone or in combination of two or more.

(D) The radical scavenger may, for example, be an anthracene compound (anthracene), a naphthoquinone compound (naphthoquinone), or a phenothiazine compound (phenothiazine).

Examples of the above hydrazine compound include p-benzoquinone, p-naphthoquinone, 2-tert-butyl-p-benzoquinone, and 2,5-diphenyl-p-benzoquinone. Examples of the naphthoquinone compound include 1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, and vitamin K.

The above-mentioned phenothiazine compound may, for example, be phenothiazine, bis(α-methylbenzyl)phenothiazine, 3,7-dioctylphthylthiazine or bis(α-dimethylbenzyl). Phthathiazine and the like.

In the resin composition, the content of the (D) radical scavenger is preferably 0.005 parts by mass or more, more preferably 0.05 parts by mass or more, based on 100 parts by mass of the (A) polypropylene resin.

In addition, the content of the (D) radical scavenger is preferably 1 part by mass or less based on 100 parts by mass of the (A) polypropylene resin.

When the content of the (D) radical scavenger is not less than the above lower limit and not more than the above upper limit, the melt tension of the modified polypropylene resin can be effectively increased. The appearance of the finally obtained foam was good.

The other components (E) contained in the resin composition other than these may be, for example, various additives.

[(E) Additives]

The (E) additive may be appropriately used depending on various purposes, and is not particularly limited.

Specific examples of the (E) additive include a weatherability stabilizer, an antistatic agent, an antioxidant, a deodorant, a photostabilizer, a crystal nucleating agent, a pigment, a lubricant, and the purpose of imparting slidability or imparting an anti-knot. A bulk surfactant, an inorganic filler, and a dispersibility improver for improving the dispersibility of the inorganic filler.

Examples of the above-mentioned dispersibility improver include a higher fatty acid, a higher fatty acid ester, and a higher fatty acid decylamine.

The above (E) additive may be contained in the above resin composition before melt kneading or during melt kneading.

Further, the (E) additive may be added to the modified polypropylene resin after being melt-kneaded.

(E) The additive may be used alone or in combination of two or more.

(Method for producing modified polypropylene resin)

In the method for producing a modified polypropylene resin, a resin composition containing (A) a polypropylene resin, (B) an organic peroxide, and (C) an aromatic vinyl monomer is melted and kneaded to obtain a modified product. Polypropylene resin.

In the method for producing a modified polypropylene resin, the resin composition in the melt kneading is used in an amount of 100 parts by mass based on the polypropylene resin. The above-mentioned organic peroxide is contained in an amount of 0.1 part by mass or more and 10 parts by mass or less based on 100 parts by mass of the polypropylene-based resin.

When the resin composition is melt-kneaded, the resin composition may be heated in a molten state.

The above resin composition can be reacted by heating during melt-kneading.

That is, the organic peroxide generates a radical by the above heating, and the radical attacks the hydrogen bonded to the tertiary carbon of the polypropylene resin to form an alkyl radical.

In addition, in the original state, β-cracking occurs and molecular cutting of the polypropylene resin occurs. Therefore, in the present embodiment, the aromatic vinyl monomer is bonded thereto to form a branched structure (crosslinked structure).

(C) The aromatic vinyl monomer is obtained by mixing the (A) polypropylene resin and the (B) organic peroxide, and then adding the mixture to the obtained mixture. good.

However, (A) a polypropylene resin, (B) an organic peroxide, and (C) an aromatic vinyl monomer may be mixed together.

(D) The radical scavenger may be added before the addition of the (C) aromatic vinyl monomer, or may be added after the addition of the (C) aromatic vinyl monomer, or may be mixed with other components.

The (E) additive may be added before the addition of the (C) aromatic vinyl monomer, or may be added after the addition of the (C) aromatic vinyl monomer, or may be mixed with other components.

Further, the resin composition can be melted and kneaded by a general machine such as a kneader, a closed kneader or an extruder.

When the above resin composition is melt-kneaded, it is preferred to use an extruder.

Further, it is preferred that the resin composition is supplied to an extruder to be cross-linked in an extruder to form a modified polypropylene resin, and the modified polypropylene resin is extruded from an extruder.

The modified polypropylene resin can be efficiently produced by continuously supplying the above resin composition to an extruder and continuously extruding the modified polypropylene resin from the extruder.

Examples of the above extruder include a single-shaft extruder and a twin-screw extruder.

The extruder may be used for producing a modified polypropylene resin, either alone or in a plurality of tandem extruders.

In particular, from the viewpoint of further improving the dispersibility and reactivity of other components of the polypropylene resin of the host resin, a twin-screw extruder is preferred.

(resin foam)

The modified polypropylene resin of the present embodiment is also suitably used in the production of a resin foam.

When the modified polypropylene resin of the present embodiment is used, a resin foam having a good appearance can be obtained.

The resin foam is preferably a polypropylene-based resin foamed sheet (hereinafter, simply referred to as "foamed sheet") which is foamed into a sheet by extrusion.

The foamed sheet may be obtained by foaming the modified polypropylene resin, for example, by using a foaming agent and modifying the modified polypropylene. The resin can be foamed.

The foamed sheet may further contain a polymer component in addition to the modified polypropylene resin.

In terms of the polymer component, an unmodified polypropylene resin is preferred.

Examples of such a polypropylene-based resin include those exemplified above as a starting material of a modified polypropylene-based resin.

In the case of a polypropylene-based resin which constitutes a foamed sheet together with a modified polypropylene-based resin, a soft system obtained by a multistage polymerization method is preferred.

In other words, the polypropylene resin is at least subjected to polymerization in the form of propylene alone or in the first stage of random copolymerization of propylene and ethylene, and after the first stage, ethylene and one or more carbon numbers of 3 or more. The at least two steps of the second stage of copolymerization of the α-olefin are preferably carried out.

Further, when the foamed sheet contains a polymer component other than the modified polypropylene resin, the modified polypropylene resin and the other polymer component may have a mass ratio of, for example, 8:2 to 2 in the foamed sheet: 8 (modified polypropylene resin: other polymers).

Further, when a polymer component other than the modified polypropylene resin is used for forming the foamed sheet, the mixture of all the polymers (including the modified polypropylene resin) contained in the foamed sheet is also The modified polypropylene resin is similarly shown to have a phase angle determined by frequency dispersion dynamic viscoelasticity measurement at 200 ° C, preferably 30° or more and 70° or less at a frequency of 0.01 Hz.

The foaming agent is not particularly limited.

The foaming agent may be a chemical foaming agent or a physical foaming agent.

The above foaming agent is preferably a volatile foaming agent.

The boiling point of the foaming agent is preferably at least the softening temperature of the modified polypropylene resin.

Examples of the foaming agent include hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, and cyclopentane, and halides thereof, carbon dioxide gas, and nitrogen gas.

The foaming agent may be used alone or in combination of two or more.

The density of the foamed sheet is preferably 0.025 g/cm ³ or more, more preferably 0.045 g/cm ³ or more.

Further, the density of the foamed sheet is preferably 0.5 g/cm ³ or less, more preferably 0.25 g/cm ³ or less.

When the density of the foamed sheet is at least the above lower limit, the rigidity and heat resistance of the foamed sheet can be improved.

When the density is less than or equal to the above upper limit, the heat insulating properties of the foamed sheet can be improved.

Further, in general, when the foaming sheet is foamed at a high expansion ratio to lower the density of the foamed sheet, the appearance of the foamed sheet tends to be deteriorated.

On the other hand, by using the modified polypropylene-based resin described above, even if the foamed sheet is foamed at a high expansion ratio and the density of the foamed sheet is lowered, a foamed sheet having a good appearance can be obtained.

The density of the foamed sheet was measured in accordance with the method described in JIS K7222:1999 "Measurement of the apparent density of foamed plastic and rubber", and specifically measured by the following method.

(density measurement method)

A sample of 100 cm ³ or more was cut out from the foamed sheet so as not to change the original cell structure, and the sample was adjusted in the No. 23/50, Class 2 environment of JIS K7100:1999 for 16 hours, and then measured. Its size and mass are then calculated by the following formula.

Apparent density (also known as apparent density) (g/cm ³ ) = mass of foam (g) / volume of foam (cm ³ )

Further, for the measurement of the test piece size, for example, "DIGIMATIC" CD-15 manufactured by Mitutoyo Corporation can be used.

The foamed sheet preferably has an open cell ratio of 30% or less, more preferably 20% or less.

The lower the above-mentioned continuous cell ratio, the better the appearance of the foamed sheet and the higher the strength of the foamed sheet.

Further, the continuous cell ratio means the ratio of the continuous bubbles in the bubble structure of the foamed sheet. The cells in which the cells of the cells (cells of the bubble structure) are continuous are called continuous bubbles, and the bubbles in which the cells are completely independent are called independent bubbles.

The open cell ratio of the above foamed sheet can be measured by the following method.

In other words, a plurality of sheets having a length of 25 mm and a width of 25 mm were cut out from the foamed sheet, and the cut sheets were placed in a measurement sample having a thickness of 25 mm without gaps therebetween, and then "Digimatic" manufactured by Mitutoyo Co., Ltd. The Caliper was measured to a size outside the sample for measurement to 1/100 mm, and the apparent volume (also referred to as apparent volume) (cm ³ ) was determined.

Next, the volume (cm ³ ) of the sample for measurement was determined by a 1-1/2-1 gas pressure method using an air comparative type hydrometer model 1000 (manufactured by Tokyo Science Co., Ltd.).

The values obtained by the above calculation were then calculated according to the following formula, and the average value of the number of the test pieces was determined.

Further, the measurement was carried out by adjusting the sample for 16 hours under the No. 23/50 and Class 2 environment of JIS K7100:1999, and then operating under the No. 23/50 and Class 2 environment of JIS K7100:1999.

At the same time, the air comparison type hydrometer is calibrated with a standard ball (large 28.9 cc, small 8.5 cc).

Open cell rate (%) = 100 × (measured volume of volume-air comparison type hydrometer) / apparent volume

In addition, the polypropylene-based resin composition containing the modified polypropylene-based resin of the present embodiment can be obtained by extrusion-foaming in a circular die or the like to obtain a foamed sheet having a beautiful appearance at a high expansion ratio.

When the rod-shaped foam and the plate-shaped foam are produced by the trimming mold, the polypropylene resin composition in a molten state in the extruder can be cooled and extruded through a mold to a specific shape.

In the meantime, the polypropylene-based resin composition of the trimming die is extruded from the extruder and does not foam until it is filled in the internal space of the mold. Therefore, the foaming is restricted to a certain extent.

At the same time, the frictional resistance generated between the rod-shaped and plate-shaped foamed molded articles extruded from the repair die and the inner wall surface of the repair die also generates a certain degree of pressure inside the mold.

Therefore, the polypropylene resin composition which is extruded from the extruder by the extruder is different from the case where the foamed sheet is produced by using a circular die or a flat die, and is not released once. pressure.

On the other hand, when a foamed sheet is produced by a circular die or the like, the polypropylene resin composition is usually extruded in an almost open space, so that rapid expansion of the volume occurs at the moment of extrusion from the die. bubble).

Therefore, in the production of the foamed sheet, unlike the extrusion foaming of the rod-shaped or plate-like foamed molded article, the polypropylene-based resin composition is subjected to high-speed shearing at the time of the slit of the mold and simultaneously increases the bubble. The stretching speed of the film.

Therefore, in the conventional modified polypropylene resin, it is difficult to form a foamed sheet having a beautiful appearance at a high expansion ratio even if a foamed molded article having a rod shape or a plate shape which is excellent in foaming state can be formed.

However, since the modified polypropylene resin of the present embodiment exhibits a specific viscoelasticity at the time of melting, a foamed sheet having a beautiful appearance can be obtained at a high expansion ratio.

Further, in the case of the modified polypropylene-based resin of the present embodiment, a particularly high-molecular-weight polymer is also produced in an article having a normal molecular weight.

Such a high molecular weight compound has a greatly different change in heating and melting compared to a polymer having a usual molecular weight, and the content in the foamed sheet is large to impair the appearance of the foamed sheet.

The proportion of such a high molecular weight compound contained in the modified polypropylene resin and the foamed sheet can be generally referred to as "colloid content".

The modified polypropylene-based resin used for forming the foamed sheet, and the foamed sheet have a colloid content of preferably 20% by mass or less, more preferably 5% by mass or less.

However, in order to make the colloid content "0% by mass", it is necessary to limit the manufacturing conditions of the modified polypropylene-based resin to a narrow range.

From such a viewpoint, the above colloid content should preferably be about 0.5 to 5% by mass.

Further, the colloidal content of the modified polypropylene resin and the foamed sheet can be determined by the following method.

[Method for measuring colloid content]

The sample can be used as it is when the object to be measured is granules, and can be cut into a square of about 1 cm when the sheet is foamed.

Then, the sample was measured by 0.8 g.

Thereafter, after the sample was boiled and heated in 80 mL of xylene for 3 hours using a Soxhlet extractor, the ruthenium solution was not cooled and filtered through a 200 mesh metal mesh.

Then, the resin insoluble matter on the metal mesh was naturally dried to evaporate the xylene in a suction cabinet, and finally the resin insoluble matter was dried together with the metal mesh at 120 ° C for 2 hours in a constant temperature drier.

After cooling in a desiccator, the mass of the metal mesh was measured, and the colloid content (% by mass) was calculated by the following formula.

Colloid content (% by mass) = insoluble resin mass on the metal mesh (g) / sample mass (0.8 g) × 100

(Insoluble resin quality on metal mesh = metal mesh quality after filtration and drying - only the quality of the metal mesh before filtration)

Further, it is preferable that the modified polypropylene resin and the foamed sheet exhibit a specific melt tension, and specifically, a melt tension of 4 cN or more and 25 cN or less at 230 ° C is preferable.

Further, the melt tension of the modified polypropylene resin and the foamed sheet can be obtained by the following method.

[Melt tension measurement method]

The sample is used as it is when the measurement target is granules. In the case of the foamed sheet, the granule chopper "Hand Truder type PM-1" manufactured by Toyo Seiki Seisakusho Co., Ltd. is used, and the cylinder temperature is 220 ° C. The sample was filled to the conditional granulator of the standby time of starting extrusion for 2.5 minutes.

The melt tension was measured by a two-hole capillary rheometer Rheologic 5000T (manufactured by CEAST, Italy).

That is, after filling the measured sample resin in a cylinder having a diameter of 15 mm heated to a test temperature of 230 ° C, the capillary of the above-mentioned measuring device was maintained at a constant maintenance piston lowering speed (0.07730 mm/s) after preheating for 5 minutes. The mold (caliber 2.095 mm, length 8 mm, inflow angle 90 degrees (tapered)) was extruded into a belt shape, and the belt was passed through a pulley of a tension detecting position of 27 cm below the capillary mold, and winding was used. The roll is wound at a starting speed of 3.94388 mm/s at a winding speed and slowly increased under an acceleration of 12 mm/s ² . The average of the maximum and minimum values before the cutting of the strip is the melting of the sample. tension.

Further, when there is only one maximum point in the tension map, the maximum value is the melt tension.

Further, the modified polypropylene resin and the foamed sheet are preferably in a state of exhibiting a specific melt mass flow rate (MFR).

Specifically, the MFR of the modified polypropylene resin and the foamed sheet is preferably 2.0 g/min or less at 230 °C.

At the same time, the MFR of the modified polypropylene resin and the foamed sheet is preferably more than 0 g/10 minutes in consideration of the load on the extruder.

Further, the MFR of the modified polypropylene resin and the foamed sheet can be obtained by the following method.

[MFR measurement method]

When the measurement target is a pellet, it can be used as a sample for measurement.

When the measurement target is a foamed sheet, the foamed sheet is used as a sample for measurement by a pelletizer "Hand Truder type PM-1" manufactured by Toyo Seiki Seisakusho Co., Ltd.

Further, when the pelletized chopper was used to form pellets from the foamed sheet, the temperature of the extrusion cylinder was 220 ° C, and the standby time from the filling of the sample to the start of extrusion was 2.5 minutes.

The melt mass flow rate (MFR) is the SEMI-AUTO MELT INDEXER 2A manufactured by Toyo Seiki Seisakusho Co., Ltd., and the melt flow rate (MFR) and melt volume melt flow rate of the plastic-thermoplastic plastic according to JIS K 7210:1999 (MVR) Test Method "B) Method for measuring the time when the piston moves by a predetermined distance as described in the B method.

The measurement conditions were: a sample amount of 3 to 8 g, a preheating time of 270 seconds, a load holding time of 30 seconds, a test temperature of 230 ° C, a test load of 21.18 N, and a piston moving distance (pitch) of 4 mm.

The number of tests was 3 times, and the average value was the value of the melt mass flow rate (g/10 minutes).

The foamed sheet of the present embodiment can be directly used as a foamed molded article such as a cushion sheet in its original state, and can also be used as a heat-formed product. A material such as a foamed molded article that imparts a three-dimensional shape.

Examples of the hot forming include vacuum forming, press forming, vacuum press forming, die forming, press molding, and the like.

In terms of the specific product produced by the thermoforming, a container is preferred.

The foamed resin container produced in this manner is not only lightweight but also high in strength, and is easy to mass-produce. Therefore, it is preferable to use it as a container for various packaging.

Further, since the foamed resin container is also excellent in heat insulating properties and the like, it is preferably used for food packaging.

The surface of the foamed molded article of the present embodiment may be laminated with a non-woven fabric, a metal foil, a decorative paper, a printed film, or the like, depending on the application.

Further, in the present embodiment, the modified polypropylene resin and the method for producing the same may be carried out as described above, but the present invention is not limited to the examples described above.

In the present embodiment, the resin foam produced from the modified polypropylene resin is exemplified only by the foamed sheet, but the modified polypropylene resin of the present invention can be widely used as a resin product other than the foamed sheet. .

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the invention is not limited by the examples.

(Example 1)

(1) Production of modified polypropylene resin

First, a polypropylene resin (homogeneous polypropylene resin, manufactured by Prime Polymer Co., Ltd., trade name "E200GP", MFR = 2.0 g/10 min, density = 0.9 g/cm ³ ), 100 parts by mass, and benzoic acid benzoic acid, third Butyl ester (manufactured by NOF Corporation, trade name "PERBUTYL Z", 1 minute half-life temperature: 166.8 ° C) 0.3 parts by mass was added to a mixer and stirred to obtain a mixture.

Then, the obtained mixture was supplied to a biaxial extruder (L/D=47) having a diameter of 30 mm, and an infusion pump was used from the middle of the twin-screw extruder to be 0.5 part by mass with respect to 100 parts by mass of the polypropylene resin. The proportion of parts by mass is supplied to the styrene monomer.

Further, the set temperature of the packing portion was 160 ° C, the temperature T1 to the styrene injection portion was 200 ° C, and the temperature T2 thereafter was 200 ° C, and then melt-kneaded in a twin-screw extruder at a number of revolutions of 72 rpm. The resin composition was extruded into a resin composition in a strand shape by a die having a diameter of 4 mm, a row length of 5 mm, and a number of holes of 2 at a tip end of the extruder at a discharge amount of 5 kg/h.

Next, the extruded strand-shaped resin composition was passed through a cooling water tank having a length of 2 m loaded with water at 30 ° C, and cooled.

Thereafter, the cooled strand-shaped resin composition was chopped by a particle chopper to obtain granules of the modified polypropylene-based resin.

(2) Production of foam

Further, 100 parts by mass of the modified polypropylene resin obtained and 0.2 parts by mass of a bubble conditioner (manufactured by Daisei Seiki Co., Ltd., trade name "FINECELL MASTER HCPO410K") were dry-blended to obtain a mixture.

Then prepare to have a caliber 50mm first extruder and caliber In-line extruder of the second extruder of 65mm, in caliber In the first extruder of 50 mm, the obtained mixture was supplied through a hopper and heated and melted.

After that, press in with a blowing agent butane (isobutane / n-butane = 70 / 30) The first extruder was melt-mixed at the same time as the above mixture.

Next, the molten mixture was transferred to a second extruder having a diameter of 65 mm and uniformly cooled to a temperature suitable for extrusion foaming, and then extruded by a cylindrical mold having a diameter of 60 mm at a discharge amount of 30 kg/hr to obtain a circle. Cylindrical foam.

The obtained cylindrical foam is further cooled inside with water of about 20 ° C. The 170 axis is cooled by the inside.

At the same time, the cylindrical foam was cooled from the outside by blowing with a blower having a diameter larger than that of the cylindrical foam.

The cooled cylindrical foam was further cut into a strip-shaped foamed sheet by a cutter at a point on the circumference.

(Examples 2 to 12, Comparative Examples 1 to 6)

The same procedure as described above was carried out except that the polypropylene resin, the amount of styrene, the type and amount of the organic peroxide used, and the set temperatures (T1, T2) of the twin screw extruder were changed as shown in the following table.

In addition, "E111G" of the table means the following polypropylene resin.

Meanwhile, the details of the organic peroxides in the table are as follows.

"E111G":

Homogeneous polypropylene resin, manufactured by Prime Polymer Co., Ltd., trade name "E111G", MFR = 0.5 g/10 min, density = 0.9 g/cm ³

"Dibutyl butyl peroxycarbonate:

Manufactured by Akzo, the product name is "Kayacarbon BIC-75", 1 minute half-life temperature: 156 °C

"Telebutyl butyl peroxy-2-ethylhexyl carbonate":

Manufactured by Akzo, the product name "Trigonox 117", 1 minute Half-life temperature: 156 ° C

"2,5-Dimethyl-2,5-di(t-butylperoxy)hexane":

Manufactured by Nippon Oil Co., Ltd. under the trade name "PERHEXA 25B", 1 minute half-life temperature: 179.8 °C

"1,1-di(t-butylperoxy)cyclohexane":

Made by Nippon Oil Co., Ltd., trade name "PERBUTYL C", 1 minute half-life temperature: 153.8 °C

(1) Production of a resin mixed with a modified polypropylene resin

(Example 13)

First, the modified polypropylene resin and soft polypropylene resin (manufactured by SunAlomer Co., Ltd., trade name "Q100 F", MFR: 0.6 g/10 min, density 0.88 g/cm ³ ) obtained in Example 11 were used. The mixing ratio was 8:2 and the mixture was stirred and mixed in a mixer to obtain a mixture.

Then, the product name "LABO PLASTOMILL" manufactured by Toyo Seiki Co., Ltd. (Model: 4M150 (body) is model: 2D15W (biaxial extruder, caliber: 15mm, L/D: 17) and attached with a diameter of 3mm The metal mold of the circular outlet was extruded into a strand shape at a discharge amount of 1.0 kg/h by setting the temperature of the entire area of the twin-screw extruder to 230 ° C while fixing the screw rotation speed to 65 rpm.

Next, the extruded resin composition was cooled by cooling in a cooling water tank having a length of 1 m while being loaded with water at 30 °C.

Thereafter, the cooled strand-shaped resin composition was chopped by a particle chopper to obtain pellets of a resin composition containing a modified polypropylene-based resin.

(2) Production of foam

The foam (foamed sheet) was produced in the same manner as in Example 1.

(Examples 14 to 17)

A foamed sheet was produced in the same manner as in Example 13 except that the mixing ratio of the resin mixed in the modified polypropylene resin was changed and the resin was mixed as described below.

The results of the evaluation of the properties of the obtained resin composition particles and the foamed sheets are shown in Table 3.

Further, the phase angle is a value at a frequency of 0.01 Hz obtained by frequency dispersion dynamic viscoelasticity measurement at 200 °C.

In addition, the criteria for determining the appearance of the foamed sheet in the table are as follows.

[Exterior]

A: It was confirmed by visual observation that the surface of the foamed sheet had no unevenness, and the surface state (smoothness) was good.

B: The surface of the foamed sheet was visually confirmed to have irregularities, but it was a practically problem-free grade.

C: Visually, it was confirmed that the surface of the foamed sheet had irregularities, or the bubble was severely broken and the surface condition was poor.

Further, in the case of Comparative Example 1, since a sufficient reforming effect was not observed, it was not evaluated.

Meanwhile, in the case of Comparative Example 3, in the MFR evaluation, fluidity was not observed under the measurement temperature and measurement was impossible.

Further, in Example 17, since the phase angle of the mixture of the modified polypropylene resin and "E200GP" was 76.1°, the apparent density and the open cell ratio were inferior to those of the foamed sheets of the other examples.

Further, the foamed sheet of Example 17 was also inferior in appearance to the foamed sheet of the other examples.

In this case, when the polymer other than the modified polypropylene resin and the modified polypropylene resin are used together as the raw material of the foamed sheet, the phase angle of the modified polypropylene resin can be made 30 to 70°. In the following, when the phase angle of the mixture of all the polymers constituting the foamed sheet is 30° or more and 70° or less, it is particularly advantageous to obtain a foamed sheet having a low open cell ratio.

As apparent from the above, in the present invention, a modified polypropylene resin which can easily produce a foamed sheet having a low open cell ratio and a foamed sheet which is excellent in a foamed state can be obtained.

Claims (7)

A modified polypropylene resin obtained by reacting an aromatic vinyl monomer in a polypropylene resin, and a phase angle obtained by measuring a dynamic viscoelasticity at a frequency of 200 ° C at a frequency of 0.01 Hz is 30 ° above 70 °. The modified polypropylene-based resin according to claim 1, wherein the melt mass flow rate is 2.0 g/10 minutes or less. A polypropylene-based resin foamed sheet comprising a modified polypropylene-based resin obtained by reacting an aromatic vinyl monomer in a polypropylene-based resin, and the modified polypropylene-based resin is dispersed at a frequency of 200 ° C The phase angle obtained by the viscoelasticity measurement is 30° or more and 70° or less at a frequency of 0.01 Hz. The polypropylene resin foamed sheet according to claim 3, further comprising a polypropylene resin different from the modified polypropylene resin. A container made of a foamed resin obtained by thermoforming a foamed sheet of a polypropylene resin as described in claim 3 or 4. A method for producing a modified polypropylene resin, which comprises reacting an aromatic vinyl monomer in a polypropylene resin to produce a modified polypropylene resin, wherein the modified polypropylene resin is produced by a method comprising The resin composition of the propylene resin, the organic oxide, and the aromatic vinyl monomer is melt-kneaded, and the phase angle obtained by measuring the dynamic viscoelasticity at a frequency of 200 ° C is measured at a frequency of 0.01 Hz. a modified polypropylene resin having a ratio of 30° or more and 70° or less; and the above-mentioned resin composition of the above-mentioned melt-kneaded resin composition is contained in an amount of 0.1 part by mass or more and 1.5 parts by mass or less based on 100 parts by mass of the polypropylene resin. The above-mentioned aromatic vinyl monomer is contained in an amount of 0.1 part by mass or more and 10 parts by mass or less based on 100 parts by mass of the polypropylene-based resin. The method for producing a modified polypropylene resin according to claim 6, wherein the organic peroxide has a structure represented by the following formula (X) Wherein R ¹ represents a substituted or unsubstituted phenyl group or a substituted or unsubstituted alkoxy group, and R ² represents a monovalent organic group.